[froggsong]

You put up the measure of your tank in cm, right? In that case, (since I'm too lazt atm to find out, lol) I'm not sure exactly how big it is. If you have seen my build log, I personally have already gone through 5? maybe 6? tubes of silicone. Now keep in mind (if you have read or are going to) that I also coated the entire inside surface of the tank with silicone to waterproof the wood, but I think I actually used less doing that than I did coating the background to press the peat moss into it. I also used GS to make "frog landings" which I also had to coat with silicone. I also had to install plexi, but most of it that I have used has been on the background. Most people say that when using clear silicone (I assume the aquarium silicone is clear), as it cures it will turn cloudy and show through if you miss any spots. The reason they use black is so that you can tell better where you are spreading it and if the peat/coco fiber/whatever falls off or you miss a spot, it doesn't show up as bad. Also, the black would look much better between the foam and the glass from the outside. Another thing, and you can weigh this with what else you have read, IMO the foam sticks better to glass than to the silicone. Some of the places that I used it in the wooden part of my tank actually peeled right off, with little effort. I think I have read people saying that it sticks better to silicone than to glass, but I can put alot of force on the landings I have in the glass part and they don't budge at all. This is just in my experience. This is the only time I have used it, so maybe I did something wrong. I think the regular silicone you bought will probably do just fine. I also think if you start out using the more expensive stuff you are either going to end up using the other stuff anyway or having to buy some more of the aquarium one. If you do use the regular stuff, just give it PLENTY of time to cure. I feel like I should add a disclaimer at the bottom of my post though... eep!